The volume and use of email has changed dramatically over the past decade. For many early users of email, notes and letters between friends could be sent and received rather quickly and without much cost. However, as the computer age has progressed, so too has the purpose of email. Email has become a critical communication medium for many businesses and organizations. As employees, for example, seek to separate more relevant messages from a swath of less relevant messages, they may tend to feel overwhelmed. This is due in large part to the great amounts of messages to read through in often very little time. Despite the changing use of email and the different behaviors of current email users, user interfaces to support email have remained relatively unchanged. Existing email user interfaces do not provide users with an effective means for assessing their email or other information, in general, in terms of importance, priority, or relevance, particularly when users are constrained by time.
Most people spend a considerable portion of time triaging their email. Those who receive large volumes of email are forced to triage their email more frequently and spend more time triaging throughout the day; failure to do so can result in an overwhelming feeling of information overload. While most people can tell the difference between strangers and the people they know well, unfortunately email clients as well as other client applications lack this basic capability. By way of example, most email clients provide only a limited set of tools to help people efficiently assess or handle their email using information such as who it is from, when it was received, and the subject. In particular, such clients are restricted to sorting this information in a fixed manner: ascending or descending (alphabetical or chronological) order. When receiving large volumes of email, this information does little to help users decide which emails are the most important or which should be handled first, especially when there is little time available to make these assessments. The most important emails given one's current context can be easily buried in the inbox and hard to find. This limits the email client's utility for helping users deal with the increasingly challenging task of managing growing volumes of content along with spam and related email fraud problems.